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Geometrical Optics - Coggle Diagram
Geometrical Optics
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Refraction
The angle of refraction is the angle defined between the normal to a surface and the refracted light ray.
Refraction occurs at the boundary of two media when light travels from one medium into the other and its speed changes but its frequency remains the same. If the light ray hits the boundary at an angle which is not perpendicular to or parallel to the surface, then it will change direction and appear to `bend'.
The refractive index (symbol n) of a material is the ratio of the speed of light in a vacuum to its speed in the material and gives an indication of how difficult it is for light to get through the material.
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Reflection
Snell's Law gives the relationship between the refractive indices, angles of incidence and reflection of two media.
The angle of incidence = The angle of reflection
The law of reflection states that the angle of reflection equals the angle of incidence: θr = θi
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Total Internal Reflection
Total internal reflection takes place when light travels from one medium to another of lower optical density. If the angle of incidence is greater than the critical angle for the medium, the light will be reflected back into the medium. No refraction takes place.
Total internal reflection is used in optical fibres in telecommunication and in medicine in endoscopes. Optical fibres transmit information much more quickly and accurately than traditional methods.
Len's Maker Formula
Lens manufacturers use the lens maker's formula to manufacture lenses of the desired focal length. The lens maker's equation is another formula used for lenses that give us a relationship between the focal length, refractive index, and radii of curvature of the two spheres used in lenses.
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Geometrical optics, or ray optics, is a model of optics that describes light propagation in terms of rays. The ray in geometric optics is an abstraction useful for approximating the paths along which light propagates under certain circumstances.
Geometrical optics does not account for certain optical effects such as diffraction and interference.
Critical Angle
The critical angle of a medium is the angle of incidence when the angle of refraction is
90 degree and the refracted ray runs along the interface between the two media.
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